Partial knee replacement surgery has become relatively common, and according to traditional practice, requires a relatively large incision in the patient in order to realign the patient's leg, remove any diseased bone and cartilage, and provide a proper surface for engagement with the tibial and femoral prostheses which must mate to form the partial knee replacement. Such large and complicated incisions increase surgical time and risk and also lengthen patient recovery. Accordingly, more recently minimally invasive techniques have become available, which greatly reduce the size of the required incision, thus providing more rapid healing and recovery for the patient. The instruments used in minimally invasive surgery clearly must be relatively small and are preferably uncomplicated, due to the space constraints within the knee. Further, these instruments must permit alignment of the knee and the proper preparation of the implant surfaces in order to receive and retain the prostheses.
When a patient's knee deteriorates, cartilage wears away, and the patient becomes bow-legged (or knock-kneed), depending upon which side of the knee is diseased. Accordingly, instruments must be used to reset the spacing between the distal femur and proximal tibia receiving the partial knee implant, to correct bow-leggedness and the patient's knock-knees. Overcorrection must be avoided, in order to avoid wear (and eventual deterioration) of the side of the knee not receiving the partial knee prosthesis.